Hand sextant



Dec. 12, 1944. E ARENA 2,364,770

HAND SEXTANT Filed se 't. 7, 1942 2 Sheets-Sheet 2 ERNzsTJ ARENA.

INVENTOR.

E05 wam Dec. 12, 1944. I E, J, ARENA 2,364,770

HAND SEXTANT Filed Sept 7, 1942 2 Sheets-Sheet l ERNEST ll ARENA 7INVENTOR.

ATTY.

Patented Dec. 12, 1944 UNITED STATES PATENT OFFICE HAND SEXTANT Ernest JArena, Hempsted, N..Y. Application September 7, 1942, Serial No. 457,555

2 Claims. c1. zit-2.4)

This invention relates to sextants and more particularly to those of thebubble type. In one of its aspects, the invention is directed to a novelsextant which is particularly adapted fr use in aircraft, although itmay be used for the.

same purpose in other places, such as marine vessels and the like.

One of the objects of this invention is to provide a hand sextant whichis mechanically simple inconstruction, may be manufactured at a rela-,

tively low cost, is rugged, and may be readily repaired when desired.

Another object ofthis invention is to provide a sextant which is simpleto operate and accurate.

Another object of this invention is to provide a sextant so shaped andbalanced, that it fits the normal hand without the necessity of handlesor hand grips, so that it may be easily and quickly manipulated by handfor the purpose of taking observation either in the daytime or at night.3

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention comprisesthe-features of construction, combination ofelements, and arrangement of parts, which will be exemplified in theconstruction hereinafter set forth, and the scope of the invention willbe indicated in the claims.

A specific embodiment of the invention is illus-" trated in theaccompanying drawings, wherein: Figure 1 is a view in side elevation andpartly in cross section and illustrates the position of the handrelative thereto in using the same.

, Figure 2 is a longitudinal section of the .sex-

tant shown in Figure 1 but with a sideplate removed.

Figure 3 is a front view of the sextant shown in Figure l.

Figure 4 is an enlarged detail sectional view of the bubble chamber andillustrates the mannor of mounting the bubble tube.

Figure 8 is an enlarged plan and sectional view illustrating themountingof the sun shades,

index mirror and index mirror arm. 7

According to the invention there are provided a pair of side plates l0and H. These side plates l0 and l I are of substantially the sameedgewise contour'and shape. The plates I0 and H are of such size andshape that the normally lower parts thereof will fit in the palm of theaverage or normal hand. Integral with plate Ill and extending therefrom,are a number of upstanding ribs |2 providing chambers for certainelements combined therewith, and also serving as spacers between theparallel plates l0 and H when assembled, as well as providing fingergrips. The upper portions of the plates l0 and H are somewhat narrowerthan the lower portions thereof, and project therefrom.

Mounted in the relatively narrow. space between the parallel side platesin and II are ,an index mirror I3, sun shades I4, eye shield l5,collimating lens l6, leveling bubble ll, bubble mirror I8, batteries 19,combined rheostat and switch 2!], and bubbleilluminating lamp 2|.

The assembly of this device is relatively simple and moreover, thearrangement of the parts is such that any repair can be carried out in asimple and expeditious manner, requiring only the replacement of anyinteriorly located part by a new part.

The index mirror I3 may be a transparent glass reflector and may bemounted on a pivotal shaft 22 as shown. The shaft ZZhas a slot thereinin which is located one end of the mirror which is demountably securedthereto by set v screw 23.

' The- 'ends'of the shaft 23 are located in opposite disposed openingsin the plates Ill and l l with the mirror l3 located between saidplates. The outer ends of the shaft 22 are of reduced diameter andbetween that portion of the shaft "22 carrying the mirror 23 of theinner sides of the side plates ID and I2 are located thrust bearings 24and side arms 25 carrying pivotally mounted sun shades I4.

By this construction, a thrust force is developed' on the thrustbearings 24, sun shade arms 25 and on the shoulders of shaft 22 becauseof their spaced relationship withthe side plates I0 and I I causing aslide springing action by side plates [0 and H on the above mentionedparts for the purpose of inducing friction between the face of thesunshade arms 25 and the adjacent parts.

This friction is utilized to maintain the'sun mounted in combination onshade supporting arms 25 and the sun shades H in any desired fixedrelation with the index mirror l3 for the purpose known to theart whiletaking an observed altitude of the sun or the moon.

It also serves to more firmly hold and posisingle sun shade, the sunshades I4 are pivotally mounted independently of each other in frames 26separated by friction washer 21 and these frames 26, together withfriction washerillare a pivot- 28 supported between the arms 25.

This spaced relationship is such that suflicient friction'is maintainedon frames 26 and'washer I:21,rzsot thatztheseczsun s-hades I 4 maybe:.-moved .ziridependently of each/other; or innn-ison; andrincombinatiorrwvitlm theaarmsz 25, land willremain in :any'idesiredselectedcposition. .The shaftt22f has ea sshoulder *.:projecting 1beyond. one of the side piateszll.

Index mirror position I indicated -on 29 is de- -fmormtablyasecuredrtowshaft 22 vz-by a friction ew'asher-SII: and screw '3 I. Bytheuse ofthis type coftmounting err-adjustment can easily be made between the.position of the index mirror. I 3::and tthe:position:oflthershaft '22.

.iPositive::indicating arm .29 cat the. same time (provides.a"po'sitive.i:lock While-11111156. =Mounted contthe outeri face-:rof Ithe plate I I .is.- .anz altitude iindicating: scale'r 32 which-recordsthe position. of the index mirron forpurposes known to the art. Theindicatingscale: 32. is inradial' relationship to theindexzmirrorpivotshaft22 aandiss'de- :mountablysecured toithe' side plate I I byscrews 'TWhiCh i ass through plate II and :make threaded engagement'withopenings. in; the ribs :12 thus acting zias :a demountable connectingdevice for1therplates hand I l.

.iSincelthe index mirror I3- has a normal requiisite'itraveliabout itspivot fulcrum of 45 in com- :bination with: the. incorporated optical:distribufifiOn *ofparts; embodied in my invention, in order"-rtor'coverxafrange of location :ofcelestial bodiesrzenith'aandgone'iwhich'is lowion the'ihorizoncor knob 39, fastenedsecurely by means of a screw 40. This thumb knob 39 and friction wheel31 coupled with three other elements permits micrometer type movement ofthe index mirror arm 29 with respect to an indicating scale 32, thuspermitting a precise and accurate reading of the graduations 34 and 36on the recording scale 29, and Vernier 35 respectively.

It will also be realized from the accompanying v.dramzings .that arelatively. rapid. movement of may beaaccompli'shed byidepressing knob39 with the thumb in the direction of side plate I l -therebydisengaging friction Wheel 31 with beveled edge of scale 32 while at thesame time pushing or pulling knob 39 in the direction andmagnituderiesired.

It is, of'course, realized that a rapid movementcofzarrmZS.andindexmirror I3 enhances the speed required to makeobservations between celestial v bodies' which have a wide spreadbetween their ealtitudes, such ;.:as at celestial .body' att or wnearvice versa. 4

r Arranged along-oneof theioptical'axes inorder todirecttheobserverseye, al-on'gthisraxis for sthipurposerof facilitatingindirect sights, Iahave provided an eye shield I5. ;Fu1ther-.:along'this-axis ;.I haveprovidedia collimatingwlensr I6, conatained'within.rarlens? holder :4 l rand held within holder :4 I .iby.- a tsnap:ring "42,1.this. lens holderAI held in position and adjustment bythreads on its lower diameter, engaging withthreadszprotvided" for same:int castingi l2.

:The purpose TOfQthiS' collimatingi lens is known to the art. Below thecollimating lens I6 and'-included within*the interior of the instru- 1ment, I have provided .a front; silvered'mirror 1'8, :placed infixed-relationto -the optical axis, arid insulated from contact wi'thcasting I2 by a gasbeing observed and altitudes ranging from O 0horizontal to 90 vertical, the recording scale '32 is1graduatedifrom 0to 101.

':Thei'lastl1iof this-flare are necessary only ':to interpolate ion thevernier scale. The degrees :between" and :on therecordingscale 32 has 55IJWEEIIZBJIIIZZQifiIld recording scale 32,:to maintain both in asemi-fixed relationr'to eachother, so

' that-under normal usage the index. mirror I3'and alarm 29 will remainin any position throughout tthennormal range :of travel ofwsame;unlessit is rdesiredfto move same -for purposes of making waaltitude'.observationsof celestial bodies, I have rzprovided a' friction wheel '31which ismounted: in

ta bearing-through arm 29 and held. against the :beveled surface ofscale-32'by' a-spring 38. At-

tached to friction wheel shaft 31 which is wan iintegraljypartrof thefriction wwheeLuls a-.;th*umb;i.75 light into the bubble:chamber, andranilluminat- 'ket 43'a1id maintaine'd in'position by a flat spring "44.The purpose ofinsulating front silvered surface of mirror I8 fromcasting I2 by gasket 43 'iS'-t0-':p1event this"'silvered surface frombeing scratched 'or marred during or after installation -01 same. 'The'purpose of this mirror [8 is to *direct the image'of the bubble 45 alongthe optical axis. 1

Arranged along'the vertical optical axis of my invention; I'haveprovideda: bubble tube I1, having a radius of curvature for" the "bubble 45'equal "-to"theffocallength of the optical system which :permits'a moreliberal alignment of the bubble with the balance'of the optical system.In'order to prevent "extraneous light'and other" unneces-"sarydetailaother than the image of the. bubble '45 and'approximating10"degrees each side of 1 the optical vertical axis of thebubble tubeI'I,*to' be viewed inthe' bubble mirror I8and thus distract the eye oftheobserver, Ihave provided aihole 46 in casting l2, large enough toaccomplish the aforementioned. The .bubble tube is held in itsrespectiveposition by asupport 41 vwhichlis maintained in correctadjustment,.alongthe center lineofthe instrument. and at. aproper anglewith. respect toJthe vertical. optical. axisLby screw stud 48. andlocked .in; position .by. a nut 49. Arrangedapproximately along thevertical optical axis and above but leadinginto the bubble chamber, of=my invention I haveprovided-a combination daylight -,-a nd night bubblechamber. illuminating device consisting of another i'lens .rholder fl..-.Included-.w-ithin'lens'holderM is a transparent dielectric window 5Il-to transmit daying lamp 2|. Lens holder 4| is made from a materialwhich is an electrical conductor thereby enabling an electrical groundto be established between one pole of the lamp 2| and casting l2 whichis the grounded side of the electrical circuit, by the medium of ,a finewire 5|. Lamp 2| screws into a threaded hole in window 50 and both areretained in the lens holder by another snap ring 42.

Electric power is supplied to lamp 2| by two batteries l9. Control ofthe lamp with respect to intensity of illumination and also the offposition of the current is accomplished by a combination switch andrheostat 20, its resistance element being connected to non-grounded sideof lamp 2|, by an insulated wire 52. The moving arm 53 of the rheostatswitch is connected to battery contacts 54, retained and insulated fromother metal contact by a dielectric cap 55 which is retained to castingl2 by screws 56 and 51 for facilitating removal and installation offresh batteries when desired, by an insulated wire 58. The opposite endof the batteries are grounded to the casting I2. Manual control ofrheostat 20 is accomplished by a knob 59 which is attached to the movingcontact arm 53 of rheostat 2!), extending to exterior of the instrumentthru side plate H! and insulated from same.

Sun shades l4 are held at rest when not in use by a spring clip 60 whichis retained to casting It by a screw 6|.

Operation of the instrument is as follows: The instrument as shown inthe accompanying drawings is designed to be held in the operators lefthand as shown in Figure 1, and operated by the right hand of theoperator. While this method is generally desirable, I do not limit thisinvention solely to this arrangement, since it will be realized that bya transposition of certain parts, the instrument may be operated by theleft hand while being held in the right hand of the operator.

It will be noted that the shape of my invention is such that it fits thecontour of the normal operators thumb 62 and the lower left portion ofthe palm 63, while gripped along the top of casting I2, with theremainder of the fingers designated 64, 65, 66 and 61. It'will also benoted that the index finger 64 can be left free if desired for thepurpose of shading the light rays during daylight which are allowed toenter the bubble chamber thru daylight window 50, thereby making itpossible to eliminate any or all extraneous light rays viewed inbubble-mirror I8.

In operating the instrument, for an indirect sight, the observers eye isplaced at A. Referring to Figures 1 and 2, so that he looks downwardlyalong one of the optical axes at an angle at the index mirror l3, andsees the image of the sun or moon reflected therein, filtered by the sunshades l4, if desired. Simultaneously, he sees the image of the bubble45, which is projected to the index mirror l3, by collimating lens l6and bubble mirror I8, in combination.

The image of the sun or moon and that of the bubble are brought intocoincidence by an adplate 35, and its graduations 36, with respect tograduations 34 on recording scale 32. i

In operating the instrument for a direct sight, the observers eye isplaced approximately at position B, as shown in Figures 1 and 2 lookingupward and through theindex mirror I3, directly at the celestial body,such as a star or planet. The index mirror I3 is then adjusted so thatthe reflected image of the bubble, illuminated sufliciently by lamp 2|,is made to coincide with the celestial body as viewed through the indexmirror I3. The angular disposition or altitude of the celestial bodybeing recorded at scale 32, and

Vernier 35, in the same manner described for an indirect sight. Both ofthese methods being well known to the art.

It will be understood that the above description and the accompanyingdrawings compre hend only the general and preferred embodiment of myinvention, and that various changes in minor details of construction,proportion and arrangement, of parts may be resorted to within the scopeof the appended claims and without sacrificing any of the advantages ofmy invention.

I claim:

l. A hand sextant comprising a pair of side plates, rib spacingmeanssecured to one of said plates and extending from the inner facethereof, an. index mirror located between said side plates atthenormally upper portion thereof, a collimating lens located betweensaid side plates and supported by said rib spacing means, a bubblemirror disposed between said side plates at the normally lower portionthereof, and demountably mounted on said rib spacing means, a levelingbubble mounted between said side plates, a transparent window supportedby said rib spacing means, a lamp supported by said window and locatedbetween said side plates, said bubble mirror, leveling bubble and lampbeing in line, a rheostat located between said side plates, and disposedadjacent and .below saidbubble mirror, an electric battery locatedbetween said side plates and supported by said rib spacing means andmeans electrically connecting in series said battery, rheostat and lamp.

2. A hand sextant comprising a. pair of side plates, rib spacing meanssecured to one of'said plates and extending from the inner face thereof,an index mirror located between said side plates at the normally upperportion thereof, a collimating lens located between said side plates andsupported by said rib spacing means, a.

bubble mirror disposed between said side plates at the normally lowerportion thereof, and demountably mounted on said rib spacing means, aleveling bubble mounted between said side plates, a transparent windowsupported by said rib spacing means, a: lamp supported by said windowand located between said side plates, said bubble mirror, levelingbubble and lamp be- 'ing in line, a rheostat located between said side

